1. Field of the Invention
The present invention relates to centrifugal pumps, and more particularly, to an improved impeller for use in a centrifugal pump. The present invention finds particular application in conjunction with an aircraft fuel pump, and it will be described with particular reference thereto. However, it will be appreciated that the present invention is also amenable to other like applications.
2. Discussion of the Art
The impeller rotates within a casing or housing of the pump. A motor rotates the impeller via a shaft which operatively connects the motor to the impeller. Fluid is provided to the impeller through, for example, a centrally disposed inlet located on one or both faces of the impeller. Fluid enters the impeller inlet in an axial direction and, due to the rotation of the impeller, is flows radially outwardly. Finally, the fluid discharges from the impeller along a peripheral edge of the impeller. Meanwhile, the fluid flowing outwardly from the impeller creates a suction at the central inlet of the impeller which serves to continuously draw more fluid into the inlet.
The fluid discharged from the impeller exits at a significantly higher pressure and velocity than when the fluid entered the impeller. The major portion of the velocity energy imparted to the fluid is converted to a pressure head by means of a volute, diffuser, or other system.
Guiding elements or blades are provided on the impeller and are of critical importance with respect to the overall efficiency of the pump. The fluid flows between the impeller blades and the overall impeller construction may be open or closed, i.e., unshrouded or shrouded, respectively. In either case, the fluid is channeled between the impeller blades (that extend axially from the base of the impeller) and the base of the impeller itself. In an open arrangement, the pump housing serves as the remaining side of the fluid passage whereas in a closed fluid flow channel the channels are enclosed by the shroud or sidewalls which rotate with and form an additional component of the impeller.
In the prior arrangements, impellers tend to have large wide-open fluid flow channels running therethrough. Typically, the cross-sectional area of the channel was at least equivalent to the cross-sectional area of the guiding elements themselves. Such an arrangement in a closed centrifugal pump resulted in a substantial amount of drag and recirculation within the channels of the impeller. As a result, the pump suffered substantial efficiency losses and consumed a large amount of power. Additionally, the recirculating fluid caused the impeller to become unstable.
Therefore, it is desirable to provide an improved impeller for centrifugal pumps that is efficient and stable. The present invention contemplates such an invention that overcomes these problems and others.
In accordance with the present invention, an improved impeller for use in a centrifugal pump is provided for minimizing the above-referenced and other disadvantages of the prior art.
In accordance with one aspect of the present invention an impeller for a centrifugal pump is provided. It has an inlet side and an outlet side. Additionally, the impeller comprises one or more fluid flow channels and a centrally disposed inlet opening. The impeller includes a base having a plurality of guiding elements extending therefrom. The fluid flow channels are defined by the guiding elements that serve to impart energy to the fluid during rotation of the impeller. A shroud encloses the fluid flow channels. The centrally disposed inlet opening admits fluid into the flow channels of the impeller to then be conducted outwardly upon rotation of the impeller.
One advantage of the present invention is that it eliminates or substantially reduces recirculation within the impeller fluid flow channels.
Another advantage of the present invention is that it substantially reduces the power required to operate the pump without reducing the pressure discharge from the pump.
Yet another advantage of the present invention is that the impeller remains balanced during rotation.
Still further advantages and benefits of the present invention will become apparent to those of ordinary skill in the art upon reading and understanding the following detailed description of the preferred embodiments.